[linux-dvb] Help with writing a DVB driver

Andreas Oberritter obi at linuxtv.org
Thu Aug 2 19:19:32 CEST 2007


Hello Thomas,

Thomas Gambier wrote:
> And now I want to start writing the video decoder part but I don't find
> any structure for the video decoder in the dvb-core I can reuse.
> 
> I tried to search for the drivers for the full-featured DVB card but I
> didn't find a structure here neither (I have to admit that I didn't
> understand well how it works).
> 
> So I'm seeking help in all kind of types (references that might be
> useful, some sites or some source code I should look...) about the
> writing of this part of the driver. But I want to stay in the DVB API
> and not going to v4l drivers or somethings... I just want to have the
> device /dev/dvb/adapter0/video0 work properly.

There is another open source driver implementing the audio and video
decoder API:

http://cvs.tuxbox.org/cgi-bin/viewcvs.cgi/tuxbox/driver/dvb/drivers/media/dvb/dbox2/Attic/dbox2_avia_av_napi.c?rev=1.1.2.1&only_with_tag=driver_2_6_branch&view=auto

The decoder APIs haven't changed much over the last years, so the old
PDF document should still be accurate enough to give a brief overview:

http://www.linuxtv.org/downloads/linux-dvb-api-1.0.0.pdf

> And last question, will a software like mplayer be able to play dvb
> streams just with the dvb drivers or does it need the /dev/video and the
> v4l drivers ?

/dev/video isn't needed. Mplayer for example has the switch -vo mpegpes,
which uses the DVB API for playback. For the "full featured" cards this
means that the TV-output is used.

However, in case you've been looking for it, there is no standard API
for using a digital video encoder or an A/V switch, to configure PAL vs.
NTSC, RGB vs. CVBS or SCART outputs etc.

The CVS tree mentioned above uses a custom interface for it (in
driver/avs and driver/saa7126).

Regards,
Andreas




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